The present invention relates to an imaging apparatus and more particularly to an electronic still-picture imaging apparatus which eliminates blooming resulting from excess electrons induced in a solid-state image sensor when it is illuminated with high intensity light.
In solid-state, or CCD (charge-coupled device) image sensors it is known that when the sensor is illuminated with high-intensity light photon-induced electrons may be generated in excess of the capacity of electron wells of the photodiode array and the excess electrons overflow from the intensely illuminated area to the outside. The result is expansion and consequent distortion of the image. One prior art solid-state image sensor has an overflow drain provided in a location adjacent the photodiodes to purge the excess electrons. However, this resduces the amount of area to be used for photoelectrical conversion with a consequential reduction of sensivity.
Another prior art image sensor as shown and described in Japanese Patent Publication No. 58-117778 (published July 13, 1983), excess electrons are purged by application of high-frequency clock pulses to vertical shift register during a constant brief interval following a read cycle. However, due to the constant interval of time, blooming cannot completely be eliminated under all lighting conditions.